Lunar Orbit: Chandrayaan-3 now 1,437km away from Moon’s surface; 100km orbit on Aug 16 | India News

BENGALURU: Isro on Wednesday guided Chandrayaan-3 even closer to the lunar surface with the completion of its third lunar-bound manoeuvre, including the lunar orbit insertion (LOI) carried out on Sunday.

“Even closer to Moon’s surface… Chandrayaan-3’s orbit is reduced to 174km x 1,437km following a manoeuvre performed today (Wednesday). The next operation is scheduled between 11.30am and 12.30pm on August 14,” Isro said.
On Monday, Isro reduced the altitude of Chandrayaan-3 by around 14,000km to bring it to 4,313km close to Moon, the next lunar-bound manoeuvres will be on August 14, when Isro will further reduce the distance between the spacecraft and Moon, on August 16, when Chandrayaan-3 enters the 100km circular orbit, and August 17, when the landing module, comprising the lander (Vikram) and the rover (Pragyan) break away from the propulsion module.

Once the landing module separates, Isro will de-boost the landing module to an orbit where the Perilune (closest point to Moon) is 30km and the Apolune is 100km. The final landing will be attempted from this orbit.
And late on Tuesday, Isro chairman S Somnath, in a lecture at an event organised by Disha Bharat, an NGO in Bengaluru, reiterated the various redundancies introduced in Chandrayaan-3 to ensure a safe landing on August 23.
Reducing Velocity Key
“The most critical part of the landing is the process of reducing the velocity of the lander from 30km height to the final landing. At 30km, the spacecraft is horizontal. Transferring the spacecraft from a horizontal orientation to vertical is very challenging, we had problems here with Chandrayaan-2. We have to ensure that not too much fuel is consumed, the distance is calculated correctly, all algorithms work… For this, we’ve changed the guidance design, introduced newer algorithms and extensive simulations have been done.” Somanath said.
As reported earlier by TOI, he pointed to various redundancies introduced in the landing module for a safe landing. Reiterating them, Somanath said: “We’ve designed it in such a way that if all the sensors fail, we will still be able to land provided that the propulsion system works. Even if two engines fail, we will be able to land.” Isro will need to use only two of the four engines on Vikram lander for the final descent.
“…The whole design is such that it should be able to handle many failures, provided that the algorithms work properly,” he added.